The present invention relates to a method and system for operating a navigation system, and more particularly to a method and system for operating a navigation system to provide road curvature.
Navigation systems are available that provide end users with various navigation-related functions and features. For example, some navigation systems are able to determine an optimum route to travel along a road network from an origin location to a destination location in a geographic region. Using input from the end user, and optionally from equipment that can determine the end user's location (such as a GPS system), the navigation system can examine various potential routes between the origin and destination locations to determine the optimum route. The navigation system may then provide the end user with information about the optimum route in the form of guidance that identifies the driving maneuvers required to be taken by the end user to travel from the origin to the destination location. The guidance may take the form of visual and/or audio instructions that are provided along the way as the end user is traveling the route. Some navigation systems are able to show detailed maps on displays outlining the route, the types of maneuvers to be taken at various locations along the route, locations of certain types of features, and so on.
In order to provide these and other navigation-related functions and features, navigation systems use geographic data. The geographic data may be in the form of one or more geographic databases that include data representing physical features in the geographic region. The geographic database includes information about the represented geographic features, such as one-way streets, position of the roads, speed limits along portions of roads, address ranges along the road portions, turn restrictions at intersections of roads, direction restrictions, such as one-way streets, and so on. Additionally, the geographic data may include points of interests, such as businesses, facilities, restaurants, hotels, airports, gas stations, stadiums, police stations, and so on.
Advanced driver assistance systems (“ADAS”) have been developed to improve the comfort, efficiency, and overall satisfaction of driving. Examples of advanced driver assistance systems include adaptive headlight aiming, adaptive cruise control, and adaptive shift control, as well as others. Some of these advanced driver assistance systems use a variety of sensor mechanisms in the vehicle to determine the current state of the vehicle and the current state of the roadway in front of the vehicle. These sensor mechanisms may include radar and vision-oriented sensors, such as cameras. Some advanced driver assistance systems also use geographic data. Geographic data from a geographic database can be used in advanced driver assistance systems to provide information about the road network, road geometry, road conditions and other items associated with the road around the vehicle. Further, geographic data can be used to determine the road ahead of the vehicle even around corners or beyond obstructions. Accordingly, geographic data can be a useful addition for some advanced driver assistance systems.
Although navigation systems and advanced driver assistance systems provide many important features, there continues to be room for new features and improvements. Some navigation system features and advanced driver assistance system features use representations of road geometry provided by the geographic data from the geographic database. The performance of these navigation system features and advanced driver assistance system features depend upon accurate representation of road geometry. Thus, there is a need to accurately and efficiently determine and provide road geometry.